(1) Field of the Invention
The present invention relates to the networking of computer systems. More specifically, the present invention relates to data transmission between networked computer systems.
(2) Description of Related Art
Typically, when a source machine sends information over a network to a destination machine, measuring the precise rates at which data flows out of the source machine over the network and into the destination machine is not crucial for the applications on the source and destination machines which facilitate the transfer of information. Though a user may be concerned with the overall transmission rate of data, the user is not concerned with where specific bottlenecks in transmitting the data may exist, since the user can not generally modify the routes over which data is transmitted on a network. However, with the sending of video and audio information or other multimedia information, the bottlenecks in sending and receiving as well as compression of the information are all crucial when attempting to synchronize different streams of multimedia data such that when played together on the destination machine, the streams appear to the user as a cohesive presentation. For instance, for video and audio, "codecs", which stands for compression/decompression determine how the multimedia data is compressed before it is sent out over the network and subsequently, how it is decompressed after it is received at the destination. However, for many different codecs, the rate at which these codes operate to compress and decompress varies depending on the resolution and sampling rate of the data that is to be used (e.g., stereo vs. mono). Further, before the data is sent out over the network the modem or Ethernet communications device which sends the compressed audio or video information from the source machine and out to the network may have its own bottlenecks which affect the overall rate of the data. During network routing of the data, the many routers and gateways that are found on the network will drastically affect the flow of data as it attempts to reach the destination. Once at the destination, the data which usually comes over the network in "packets", must be reassembled and sequenced such that it can be decompressed and played or saved on the destination machine. The reassembly and also the decompression of the video and audio data also affects the ability of the multimedia presentation to be coherent and in real time. Often in a multimedia presentation, having both video and audio, the rates at which video stream and the audio stream are played must be synchronized properly if they are to appear as one coherent presentation to the user.
Thus, there is a need to be able to detect the various rates at which information is compressed, transmitted, sequenced and decompressed such that the rates and potential bottlenecks may be reported to a user or to a program to allow a better synchronization of multimedia data streams.